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    Subject[PATCH 4.19 150/152] netfilter: ipt_CLUSTERIP: fix sleep-in-atomic bug in clusterip_config_entry_put()
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Taehee Yoo <ap420073@gmail.com>

    commit 2a61d8b883bbad26b06d2e6cc3777a697e78830d upstream.

    A proc_remove() can sleep. so that it can't be inside of spin_lock.
    Hence proc_remove() is moved to outside of spin_lock. and it also
    adds mutex to sync create and remove of proc entry(config->pde).

    test commands:
    SHELL#1
    %while :; do iptables -A INPUT -p udp -i enp2s0 -d 192.168.1.100 \
    --dport 9000 -j CLUSTERIP --new --hashmode sourceip \
    --clustermac 01:00:5e:00:00:21 --total-nodes 3 --local-node 3; \
    iptables -F; done

    SHELL#2
    %while :; do echo +1 > /proc/net/ipt_CLUSTERIP/192.168.1.100; \
    echo -1 > /proc/net/ipt_CLUSTERIP/192.168.1.100; done

    [ 2949.569864] BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
    [ 2949.579944] in_atomic(): 1, irqs_disabled(): 0, pid: 5472, name: iptables
    [ 2949.587920] 1 lock held by iptables/5472:
    [ 2949.592711] #0: 000000008f0ebcf2 (&(&cn->lock)->rlock){+...}, at: refcount_dec_and_lock+0x24/0x50
    [ 2949.603307] CPU: 1 PID: 5472 Comm: iptables Tainted: G W 4.19.0-rc5+ #16
    [ 2949.604212] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015
    [ 2949.604212] Call Trace:
    [ 2949.604212] dump_stack+0xc9/0x16b
    [ 2949.604212] ? show_regs_print_info+0x5/0x5
    [ 2949.604212] ___might_sleep+0x2eb/0x420
    [ 2949.604212] ? set_rq_offline.part.87+0x140/0x140
    [ 2949.604212] ? _rcu_barrier_trace+0x400/0x400
    [ 2949.604212] wait_for_completion+0x94/0x710
    [ 2949.604212] ? wait_for_completion_interruptible+0x780/0x780
    [ 2949.604212] ? __kernel_text_address+0xe/0x30
    [ 2949.604212] ? __lockdep_init_map+0x10e/0x5c0
    [ 2949.604212] ? __lockdep_init_map+0x10e/0x5c0
    [ 2949.604212] ? __init_waitqueue_head+0x86/0x130
    [ 2949.604212] ? init_wait_entry+0x1a0/0x1a0
    [ 2949.604212] proc_entry_rundown+0x208/0x270
    [ 2949.604212] ? proc_reg_get_unmapped_area+0x370/0x370
    [ 2949.604212] ? __lock_acquire+0x4500/0x4500
    [ 2949.604212] ? complete+0x18/0x70
    [ 2949.604212] remove_proc_subtree+0x143/0x2a0
    [ 2949.708655] ? remove_proc_entry+0x390/0x390
    [ 2949.708655] clusterip_tg_destroy+0x27a/0x630 [ipt_CLUSTERIP]
    [ ... ]

    Fixes: b3e456fce9f5 ("netfilter: ipt_CLUSTERIP: fix a race condition of proc file creation")
    Signed-off-by: Taehee Yoo <ap420073@gmail.com>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/ipv4/netfilter/ipt_CLUSTERIP.c | 19 ++++++++++++++-----
    1 file changed, 14 insertions(+), 5 deletions(-)

    --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
    +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
    @@ -56,7 +56,7 @@ struct clusterip_config {
    #endif
    enum clusterip_hashmode hash_mode; /* which hashing mode */
    u_int32_t hash_initval; /* hash initialization */
    - struct rcu_head rcu;
    + struct rcu_head rcu; /* for call_rcu_bh */
    struct net *net; /* netns for pernet list */
    char ifname[IFNAMSIZ]; /* device ifname */
    };
    @@ -72,6 +72,8 @@ struct clusterip_net {

    #ifdef CONFIG_PROC_FS
    struct proc_dir_entry *procdir;
    + /* mutex protects the config->pde*/
    + struct mutex mutex;
    #endif
    };

    @@ -118,17 +120,18 @@ clusterip_config_entry_put(struct cluste

    local_bh_disable();
    if (refcount_dec_and_lock(&c->entries, &cn->lock)) {
    + list_del_rcu(&c->list);
    + spin_unlock(&cn->lock);
    + local_bh_enable();
    /* In case anyone still accesses the file, the open/close
    * functions are also incrementing the refcount on their own,
    * so it's safe to remove the entry even if it's in use. */
    #ifdef CONFIG_PROC_FS
    + mutex_lock(&cn->mutex);
    if (cn->procdir)
    proc_remove(c->pde);
    + mutex_unlock(&cn->mutex);
    #endif
    - list_del_rcu(&c->list);
    - spin_unlock(&cn->lock);
    - local_bh_enable();
    -
    return;
    }
    local_bh_enable();
    @@ -278,9 +281,11 @@ clusterip_config_init(struct net *net, c

    /* create proc dir entry */
    sprintf(buffer, "%pI4", &ip);
    + mutex_lock(&cn->mutex);
    c->pde = proc_create_data(buffer, 0600,
    cn->procdir,
    &clusterip_proc_fops, c);
    + mutex_unlock(&cn->mutex);
    if (!c->pde) {
    err = -ENOMEM;
    goto err;
    @@ -833,6 +838,7 @@ static int clusterip_net_init(struct net
    pr_err("Unable to proc dir entry\n");
    return -ENOMEM;
    }
    + mutex_init(&cn->mutex);
    #endif /* CONFIG_PROC_FS */

    return 0;
    @@ -841,9 +847,12 @@ static int clusterip_net_init(struct net
    static void clusterip_net_exit(struct net *net)
    {
    struct clusterip_net *cn = clusterip_pernet(net);
    +
    #ifdef CONFIG_PROC_FS
    + mutex_lock(&cn->mutex);
    proc_remove(cn->procdir);
    cn->procdir = NULL;
    + mutex_unlock(&cn->mutex);
    #endif
    nf_unregister_net_hook(net, &cip_arp_ops);
    }

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